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Phase transitions in the frustrated Ising ladder with stoquastic and nonstoquastic catalysts

Physical Review Research 2021年第4期3卷 043013-043013页

作者： Kabuki Takada Shigetoshi Sota Seiji Yunoki Bibek Pokharel Hidetoshi Nishimori Daniel A. Lidar Department of Physics Tokyo Institute of Technology Yokohama Kanagawa 226-8503 Japan Computational Materials Science Research Team RIKEN Center for Computational Science (R-CCS) Kobe Hyogo 650-0047 Japan Computational Condensed Matter Physics Laboratory RIKEN Cluster for Pioneering Research (CPR) Wako Saitama 351-0198 Japan Computational Quantum Matter Research Team RIKEN Center for Emergent Matter Science (CEMS) Wako Saitama 351-0198 Japan Department of Physics University of Southern California Los Angeles California 90089 USA Center for Quantum Information Science & Technology University of Southern California Los Angeles California 90089 USA Institute of Innovative Research Tokyo Institute of Technology Yokohama Kanagawa 226-8503 Japan Graduate School of Information Sciences Tohoku University Sendai Miyagi 980-8579 Japan RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) Wako Saitama 351-0198 Japan Department of Electrical & Computer Engineering and Department of Chemistry University of Southern California Los Angeles California 90089 USA

The role of nonstoquasticity in the field of quantum annealing and adiabatic quantum computing is an actively debated topic. We study a strongly-frustrated quasi-one-dimensional quantum Ising model on a two-leg ladder to elucidate how a first-order phase transition with a topological origin is affected by interactions of the ±XX-type. Such interactions are sometimes known as stoquastic (negative sign) and nonstoquastic (positive sign) “catalysts”. Carrying out a symmetry-preserving real-space renormalization group analysis and extensive density-matrix renormalization group computations, we show that the phase diagrams obtained by these two methods are in qualitative agreement with each other and reveal that the first-order quantum phase transition of a topological nature remains stable against the introduction of both XX-type catalysts. This is the first study of the effects of nonstoquasticity on a first-order phase transition between topologically distinct phases. Our results indicate that nonstoquastic catalysts are generally insufficient for removing topological obstacles in quantum annealing and adiabatic quantum computing.

关键词： Adiabatic quantum optimization Phase transitions by order Quantum spin models Density matrix renormalization group Renormalization group

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Light-Based Analog Computing Using a Single Array of Polarizable Particles 12

Light-Based Analog Computing Using a Single Array of Polariz...

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12th International Congress on Artificial Materials for Novel Wave Phenomena, METAMATERIALS 2018

作者： Rardi, Y. Alu, A. Department of Electrical and Computer Engineering University of Texas at Austin AustinTX78712 United States Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Physics Program Graduate Center City University of New York New YorkNY10016 United States Department of Electrical Engineering City College of New York New YorkNY10031 United States

ISBN: (纸本)9781538647028

Light-based signal processing in the spatial domain enables parallel computation, resulting in faster operations in comparison to digital-based systems. We propose a basic platform to realize spatial differentiation and integration of the impinging wavefront using a basic array of electric/magnetic dipoles. We also leverage bianisotropic inclusions to realize odd operations on the impinging wavefront. Our results show that a single array of polarizable particles enables sufficient degrees of freedom to realize optical analog computing using metasurfaces. © 2018 IEEE.

关键词： Wavefronts

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Metagratings for Efficient Wavefront Manipulation 12

Metagratings for Efficient Wavefront Manipulation

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12th International Congress on Artificial Materials for Novel Wave Phenomena, METAMATERIALS 2018

ISBN: (纸本)9781538647028

Metagratings are two-dimensional periodic arrays of individual scatterers that enable highly-efficient extreme wave transformation which was impossible using conventional metasurfaces. We review our recent progress in this area and, notably, discuss metagrating designs based on asymmetric electric dipoles that are practically easier to realize compared to bianisotropic inclusions. In addition, we present the design of a tunable metagrating based on graphene strips. It will be shown that the proposed structure can provide multiple functionalities by tuning just two bias voltages. The efficiency of the proposed design is only limited by dissipation in graphene. © 2018 IEEE.

关键词： Graphene

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A blind deconvolution approach to discontinuity location and characterization in ultrasonic nondestructive testing

A blind deconvolution approach to discontinuity location and...

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European Signal Processing Conference (EUSIPCO)

作者： Giovanni A. Guarneri Daniel R. Pipa Flávio Neves Lúcia V. R. de Arruda Graduate Program in Electrical Engineering (PPGEE) Federal University of Technology - Paraná (UTFPR) Pato Branco Paraná Brazil Graduate Program in Electrical and Computer Engineering (CPGEI) Federal University of Technology - Paraná (UTFPR) Curitiba Paraná Brazil

This paper presents a new algorithm for discontinuity location and characterization using A-scan signals from an ultrasonic inspection system. The algorithm is based on solving an inverse problem in which the observation model is different from that traditionally used. In this model, the input vector represents the location of the geometrical center of the discontinuity and the scattering amplitude of the discontinuity is embedded in the impulse response of the ultrasonic inspection system. First, we jointly estimate the locations and the scattering amplitudes of the discontinuities from the acquired signals. Then, the geometrical parameters of the discontinuities are calculated from the estimated scattering amplitude. The method is tested to characterize side-drilled holes using both synthetic and real data. The results demonstrates the effectiveness of the algorithm.

关键词： Signal processing algorithms Synchronous digital hierarchy Scattering Transducers Acoustics Approximation algorithms Europe

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Piezoelectric Topological Insulators for Acoustic Waves

Piezoelectric Topological Insulators for Acoustic Waves

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International Congress on Advanced Electromagnetic Materials in Microwaves and Optics (METAMATERIALS)

作者： D. L. Sounas A. Alù Department of Electrical and Computer Engineering University of Texas at Austin Austin TX USA Physics Program Graduate Center City University of New York New York NY USA

We present topological insulators for surface acoustic waves on piezoelectric materials. Our structures are based on honeycomb lattices of different types of acoustic domains and derive their nontrivial topology by breaking the symmetry of the lattice hexagonal unit cells. Our results can have applications in compact signal processing integrated devices at microwave frequencies based on surface acoustic waves.

关键词： Lattices Photonics Topological insulators Acoustic waves Surface acoustic wave devices Piezoelectric materials

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Physics-based learned design: Optimized coded-illumination for quantitative phase imaging

arXiv

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arXiv 2018年

作者： Kellman, Michael R. Bostan, Emrah Repina, Nicole Waller, Laura Department of Electrical Engineering and Computer Sciences University of California BerkeleyCA94720 United States Graduate Program in Bioengineering University of California BerkeleyCA94720 United States

Coded-illumination can enable quantitative phase microscopy of transparent samples with minimal hardware requirements. Intensity images are captured with different source patterns and a non-linear phase retrieval optimization reconstructs the image. The non-linear nature of the processing makes optimizing the illumination pattern designs complicated. Traditional techniques for experimental design (e.g. condition number optimization, spectral analysis) consider only linear measurement formation models and linear reconstructions. Deep neural networks (DNNs) can efficiently represent the non-linear process and can be optimized over via training in an end-to-end framework. However, DNNs typically require a large amount of training examples and parameters to properly learn the phase retrieval process, without making use of the known physical models. Here, we aim to use both our knowledge of the physics and the power of machine learning together. We develop a new data-driven approach to optimizing coded-illumination patterns for a LED array microscope for a given phase reconstruction algorithm. Our method incorporates both the physics of the measurement scheme and the non-linearity of the reconstruction algorithm into the design problem. This enables efficient parameterization, which allows us to use only a small number of training examples to learn designs that generalize well in the experimental setting without retraining. We show experimental results for both a well-characterized phase target and mouse fibroblast cells using coded-illumination patterns optimized for a sparsity-based phase reconstruction algorithm. Our learned design results using 2 measurements demonstrate similar accuracy to Fourier Ptychography with 69 measurements. Copyright © 2018, The Authors. All rights reserved.

关键词： Statistics

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Multi-UAVs communication for payload data link enhancement under asynchronous access

Multi-UAVs communication for payload data link enhancement u...

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International Conference on Wireless and Optical Communications ( WOCC)

作者： Yun-Ruei Li Hsin-Piao Lin Li-Chun Wang Abebe Belay Adege Li-Yong Chen Department of Electronic Engineering National Taipei University of Technology Taipei Taiwan Department of Electrical Engineering National Chiao Tung University Hsinchu Taiwan Department of International Graduate Program in Electrical Engineering and Computer Science (EECS) National Taipei University of Technology Taipei Taiwan

Recently, unmanned Aerial Vehicles (UAVs) are widely applied in civilian and commercial areas. In order to rapidly arrange the UAVs in a variable and changeable environment, the technique of maintaining stable and reliable communication link between Ground Control Station (GCS) and UAVs is one of the main issues [1]. However, UAVs deployment can significantly increase the efficiency of missions execution and the flexibility of task allocation. As discussed by different scholars, multi-UAVs have a number of advantages depending on the application areas: disaster areas monitoring, wireless sensor data collection in precision agriculture, and relay-aided of UAVs network topology [2].

关键词： OFDM Resource management Interference Wireless communication Payloads Bandwidth Optical filters

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Lattice dynamics localization in low-angle twisted bilayer graphene

arXiv

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arXiv 2020年

作者： Gadelha, Andreij C. Ohlberg, Douglas A.A. Rabelo, Cassiano Neto, Eliel G.S. Vasconcelos, Thiago L. Campos, João L. Lemos, Jessica S. Ornelas, Vinícius Miranda, Daniel Nadas, Rafael Santana, Fabiano C. Watanabe, Kenji Taniguchi, Takashi van Troeye, Benoit Lamparski, Michael Meunier, Vincent Nguyen, Viet-Hung Paszko, Dawid Charlier, Jean-Christophe Campos, Leonardo C. Cançado, Luiz G. Medeiros-Ribeiro, Gilberto Jorio, Ado Physics Department Electrical Engineering Graduate Program Computer Science Department Universidade Federal de Minas Gerais Belo HorizonteMG31270-901 Brazil Physics Institute Universidade Federal da Bahia Campus Universitário de Ondina Salvador - BA40170-115 Brazil Divisão de Metrologia de Materiais Inmetro Duque de Caxias RJ25250-020 Brazil 1-2-1 Sengen Tsukuba-cityIbaraki305-0047 Japan Physics Applied Physics and Astronomy Jonsson Rowland Science Center Room 1C25 110 8th Street TroyNY12180 United States Louvain-la-Neuve Belgium

A low twist angle between the two stacked crystal networks in bilayer graphene enables self-organized lattice reconstruction with the formation of a periodic domain. This superlattice modulates the vibrational and electronic structures, imposing new rules for electron-phonon coupling and the eventual observation of strong correlation and superconductivity. Direct optical images of the crystal superlattice in reconstructed twisted bilayer graphene are reported here, generated by the inelastic scattering of light in a nano-Raman spectroscope. The observation of the crystallographic structure with visible light is made possible due to lattice dynamics localization, the images resembling spectral variations caused by the presence of strain solitons and topological points. The results are rationalized by a nearly-free-phonon model and electronic calculations that highlight the relevance of solitons and topological points, particularly pronounced for structures with small twist angles. We anticipate our discovery to play a role in understanding Jahn-Teller effects and electronic Cooper pairing, among many other important phonon-related effects, and it may be useful for characterizing devices in the most prominent platform for the field of *** Codes 82D03 Copyright © 2020, The Authors. All rights reserved.

关键词： Electronic structure

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All-optical reconfigurable chiral meta-molecules

arXiv

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arXiv 2019年

作者： Lin, Linhan Lepeshov, Sergey Krasnok, Alex Jiang, Taizhi Peng, Xiaolei Korgel, Brian A. Alu, Andrea Zheng, Yuebing Department of Mechanical Engineering University of Texas at Austin AustinTX78712 United States Materials Science & Engineering Program Texas Materials Institute University of Texas at Austin AustinTX78712 United States ITMO University St. Petersburg197101 Russia Department of Electrical and Computer Engineering University of Texas at Austin AustinTX78712 United States Mc Ketta Department of Chemical Engineering University of Texas at Austin AustinTX78712 United States Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Physics Program Graduate Center City University of New York NY10016 United States Department of Electrical Engineering City College of The City University New YorkNY10031 United States

Chirality is a ubiquitous phenomenon in the natural world. Many biomolecules without inversion symmetry such as amino acids and sugars are chiral molecules. Measuring and controlling molecular chirality at a high precision down to the atomic scale are highly desired in physics, chemistry, biology, and medicine, however, have remained challenging. Herein, we achieve all-optical reconfigurable chiral meta-molecules experimentally using metallic and dielectric colloidal particles as artificial atoms or building blocks to serve at least two purposes. One is that the on-demand meta-molecules with strongly enhanced optical chirality are well-suited as substrates for surface-enhanced chiroptical spectroscopy of chiral molecules and as active components in optofluidic and nanophotonic devices. The other is that the bottom-up-assembled colloidal meta-molecules provide microscopic models to better understand the origin of chirality in the actual atomic and molecular systems. Copyright © 2019, The Authors. All rights reserved.

关键词： Atoms

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Inverse-designed photonic circuits for fully passive, bias-free Kerr-based nonreciprocal transmission and routing

arXiv

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arXiv 2019年

作者： Yang, Ki Youl Skarda, Jinhie Cotrufo, Michele Dutt, Avik Ahn, Geun Ho Vercruysse, Dries Fan, Shanhui Alù, Andrea Vucković, Jelena E. L. Ginzton Laboratory Stanford University StanfordCA94305 United States Department of Electrical and Computer Engineering University of Texas at Austin AustinTX78712 United States Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Physics Program Graduate Center City University of New York New YorkNY10016 United States Department of Electrical Engineering City University of New York New YorkNY10031 United States

Nonreciprocal devices such as isolators and circulators are key enabling technologies for communication systems, both at microwave and optical frequencies. While nonreciprocal devices based on magnetic effects are available for free-space and fibre-optic communication systems, their on-chip integration has been challenging, primarily due to the concomitant high insertion loss, weak magneto-optical effects, and material incompatibility. We show that Kerr nonlinear resonators can be used to achieve all-passive, low-loss, bias-free, broadband nonreciprocal transmission and routing for applications in photonic systems such as chip-scale LIDAR. A multi-port nonlinear Fano resonator is used as an on-chip, all-optical router for frequency comb based distance measurement. Since time-reversal symmetry imposes stringent limitations on the operating power range and transmission of a single nonlinear resonator, we implement a cascaded Fano-Lorentzian resonator system that overcomes these limitations and significantly improves the insertion loss, bandwidth and non-reciprocal power range of current state-of-the-art devices. This work provides a platform-independent design for nonreciprocal transmission and routing that are ideally suited for photonic integration. Copyright © 2019, The Authors. All rights reserved.

关键词： Insertion losses

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